Proximity control for a vending machine



United States Patent 3,428,157 PROXIMITY CONTROL FOR A VENDING MACHINE Robert E. Patterson, Raytown, and James F. Ptacek, Kansas City, Mo., assiguors to The Vendo Company, Kansas City, Mo., a corporation of Missouri Filed Feb. 16, 1967, Ser. No. 616,508

US. Cl. 1942 Claims Int. Cl. G07f 7/00, 11/00 ABSTRACT OF THE DISCLOSURE A customer of a multiple selection vending machine accomplishes the selection of a desired article by moving his hand into close proximity to a conductive plate representing the desired article. The presence of the customers hand is sensed and, if proper coinage has been deposited, the vend cycle commences and the article is dispensed. A capacity controlled sensing circuit is connected to the selector plate, the increase in capacitance between the plate and the machine chassis resulting from the presence of the customers body adjacent the plate being utilized to cause the circuit to initiate the selective vend.

The sensing circuits and associated plates form a part of a proximity detector having an oscillator which continuously delivers a signal to each of the circuits. The incoming signal is rectified in each circuit, the opposite polarity components of the signal then being fed to a summer which adds the average values of the two components. The selector plate is connected to the summer to add capacitance thereto when an increased capacitance is exhibited by the plate due to the presence of the customer. In such condition, the summer and the plate cooperate to form a filter network for one of the signal components, thereby raising the average value at the summation output when the customer touches or is in close proximity to the plate.

The primary object of this invention is to provide a multiple selection vending machine in which articles are selected by a customer for vending by the machine without the use of push button switches, pull knobs or other manually operable devices commonly employed in conventional vending apparatus.

As a corollary to the foregoing object, it is an important aim of this invention to provide a vending machine in which an article is selected by merely placing the hand in close proximity to a selector plate representing the desired article. Manifestly, through the use of a plurality of customer accessible plates representing the various articles available for selection, the aforesaid switches or knobs are eliminated to increase customer convenience and reduce the number of moving parts in the machine. Additionally, proximity control facilitates the use of electrical circuitry rather than mechanical linkages between the selecting and dispensing subassemblies of the machine.

Furthermore, it is an important object of the instant invention to provide a vending machine as aforesaid having an electrically operated selection interlock, and logic circuitry which prevents deposit information from reaching the vend control apparatus of the machine after commencement of a vend cycle.

Another important object is to provide a novel proximity detector which employs capacity sensing and indicates the presence or absence of an adjacent foreign body by the DC level of an output signal produced by the detector.

In the drawing:

FIGURE 1 is a fragmentary, front elevational view of a vending machine;

FIG. 2 is a block and logic diagram of the vending system;

FIG. 3 is a timing graph illustrating the operation of the system;

FIG. 4 is an electrical schematic diagram of an interlock circuit; and

FIG. 5 is a schematic diagram of one of the sensing circuits of the proximity detector.

A portion of the front panel 10 of a multiple selection vending machine is shown in FIG. 1. Four display compartments 12 in the cabinet behind the front panel permit the customer to view samples of the articles available for selection. A row of sensing components in the nature of circular, conductive plates 14 are mounted in front of display compartments 12, each plate 14 being disposed adjacent the bottom of a corresponding compartment 12 and in central alignment therewith so that a customer will visually associate a particular plate 14 with a corresponding compartment 12. Plates 14 replace the usual row of selector buttons or pull knobs employed in conventional vending apparatus and are mounted such that the customer in making a selection merely touches a selector plate or places his hand in close proximity thereto. A coin slot 16 and a coin return lever 18 are also illustrated in FIG. 1.

Referring to FIG. 2, each plate 14 is electrically connected to a sensing circuit 20, four such circuits being illustrated in block diagram form corresponding to the four selector plates 14. A high frequency oscillator 22 delivers a sinusoidal output and is coupled to the four sensing circuits 20. The output frequency of oscillator 22 is not critical, 500 kHz. being satisfactory. Oscillator 22 and circuit 20 comprise the proximity detector of the instant invention and will be described in detail following the overall description of the system.

Coin switches 24 are disposed in the coin tracks of the coin acceptor of the machine, the tracks communicating with coin slot 16 in the conventional manner. As coin switches 24 are actuated by deposited coins, the switches control the operation of a totalizer 26 which registers the accumulated deposit through a stepper relay arrangement or solid state totalization circuitry. Ten cent, 15 and 25 credit lines 28, 30 and 32, respectively, are shown con nected to the inputs of three AND gates 34, 36 and 38. Totalizer 26 triggers oscillator 22 when the first coin is deposited regardless of whether or not sufiicient credit for a vend is established by the first deposit, this function being illustrated by line 40 interconnecting totalizer 26 and oscillator 22. In practice, oscillator turn-on may be achieved by routing the power connections of the oscillator stage through the appropriate switching element of the totalizer.

The outputs of AND gates 34, 36 and 38 are connected to the contacts of four rotary price setting switches 42, 44, 46 and 48, the movable poles of these switches being connected to the inputs of AND gates 50, 52, 54 and 5-6 respectively. The various AND gates illustrated in FIG. 2 are of the two input type, the second input of each of the gates 50, 52, 54 and 56 being connected to the output of a corresponding sensing circuit 20.

Interlock and selection control circuitry 58 operates in response to the outputs of AND gates 50, 52, 54 and 56 in a manner to be fully described hereinafter, it being suflicient at this juncture to understand that circuitry 58 prevents a multiple vend from being initiated by an unscrupulous customer, serves as a memory of the selection, and starts a timer 60 which, in turn, controls other sequentially occurring functions of the vending system. Timer 60 may be of the RC electronic type and, during its timing cycle, causes acceptance of coins in escrow, delivers a vend pulse along a line '62, inhibits the scavenging of deposited coins, and ultimately resets totalizer 26 along a line 64-. The coin acceptance function, in one conventional form of coin acceptor, is effected by the energization of a solenoid which, in turn, operates a a gate in the escrow to direct the deposited coins to the coin box of the machine. Such solenoid or its functional equivalent is illustrated diagrammatically at 66-.

Another gate in the escrow (under customer control) may be provided to permit return of the deposited coins to the customer through a coin return chute; thus, operation of this gate must be prevented at the time of acceptance, this function being illustrated by a block 68 labeled Scavenge Inhibit which also receives the accept command from timer 60. If the return of coins to the customer before selection is solenoid-controlled, the scavenge inhibiter 68 may take the form of contacts in series with the solenoid which open in response to the accept command. A block 70 labeled Scavenge represents the coin return structure and, if operated by the customer, resets the totalizer 26 to the zero credit condition as illustrated by reset line 72.

Four outputs 74, 76, 78 and 80 from the interlock and selection control circuitry 58 are connected to the inputs of four AND gates 82, 84, 86 and 88 respectively. The outputs of these AND gates are connected to four article dispensing structures 90, 92, 94 and 96. Each structure is illustrated as comprising a vend solenoid which is energized by a driver in response to an output from the associated AND gates '82, 84, 86 or 88.

A four input NOR gate 98 has its output connected to one input of each of the AND gates 34, 36 and 38. The inputs of the NOR gate 98 are connected to outputs 74, 76, 78 and 80 of circuitry 58.

Referring to FIG. 5, oscillator 22 is shown in association with one of the sensing circuits 20 and its associated selector plate 14. The output of oscillator 22 is rectified by a pair of diodes 100 and 102, each diode being connected to one leg of a summer network having an output 104. The diodes are oppositely poled, hence half cycles of one polarity of the oscillator output are introduced to a resistor 106 connected in series between diode 100 and output terminal 104. Similarly, half cycles of opposite polarity are fed to a resistor 108 connected in series between diode 102 and terminal 104. Plate 14 is connected to the input of resistive leg 108, an adjustable neutralizing capacitor 110 being connected between the input of resistive leg 106 and ground. A condenser of substantially greater capacity than neutralizing capacitor 110 is connected between terminal 104 and ground and cooperates with resistor 106 and 108 to provide a summation at terminal 104 of the average values of the two opposite polarity components of the output signal from oscillator 22.

The ground notation illustrated in FIG. represents chassis ground of the machine. The conductive structural assembly of the machine, including panel 10, is maintained at chassis ground potential. The stray capacitance of plate 14 is illustrated at 112 and represents the capacity between plate 14 and the structural assembly of the machine.

FIGURE 4 illustrates an exemplary electronic interlock circuit utilizing four silicon controlled rectifiers 114, 116, 118 and 120. The cathodes of the SCRs are maintained at chassis ground, the gates 114a, 116a, 118a and 120a thereof being connected to the outputs of AND gates 50, 52, 54 and 56 respectively. The anodes of the SCRs are interconnected by three commutating capacitors 122 and each anode is connected to a positive potential through a load resistor. Leads 124, 126, 128 and 130 are connected to the anodes of respective SCRs 11-4, 116, 11 8 and 120 and, in incorporating the circuit of FIG. 4 into the composite interlock and selection control circuit 58, these leads are coupled to outputs 74,

76, 78 and 80 respectively.

Operation With the apparatus in standby, outputs 74, 76, 78 and are at the 0 logic level, binary logic being utilized throughout the system. Thus, the output of NOR gate 98 is at the 1 level. When the customer deposits coinage in the machine, oscillator 22 is rendered operative and, after all coins are deposited, the totalizer registers the total value of the credit established. Initiation of the oscillator and the establishment of total credit is illustrated in the timing graph of FIG. 3, the break symbols indicating that the total duration of oscillator operation and the time during which total credit is registered will vary, depending upon the number of coins deposited and the speed with which the customer feeds coins into the machine and makes his selection. In the event that, for

example, a 10 article is desired and a dime is deposited, it will be appreciated that oscillator turn-on and credit establishment would commence at the same time.

It will be assumed that the customer desires an article of the type displayed in the first or leftmost compartment 12, and that the first sensing circuit 20, AND gates 50 and 82, and structure represent the subassemblies of the apparatus associated exclusively with the vending of such an article. Price setter 42 is set to interconnect AND gates 38 and 50, thus a deposit of 20 is required in order to obtain the desired article. However, the price setter 48 for another article available for selection is also set at a price of 20; therefore, when the totalizer registers 20 and delivers an output at the 1 level along line 32, the output of AND gate 38 will deliver a logic 1 output to one input of each of the AND gates 50 and 56. Neither of the AND gates 50 or 56 respond at this time since the other input of each gate remains at the 0 level until a selection is made.

After depositing the required coinage, the customer makes his selection by touching the first plate 14 or by moving his hand into close proximity thereto, whereupon the capacitance between the input of resistance leg 108 and ground increases substantially. If the customer touches plate 14, his body materially increases the effective size of the plate thereby causing the plate and the chassis of the machine to form a capacitor. If the hand is brought into close proximity to plate 14 without touching the latter, then the body of the customer acts as a series capacitor between plate 14 and chassis ground with the same overall effect. In standby, neutralizing capacitor offsets the effect of the stray capacitance 112, and the output at terminal 104 is zero since the average values of the two opposite polarity components of the output of oscillator 22 in the respective summer legs are equal, resulting in a cancellation at terminal 104. However, when the capacitance in resistor leg 108 increases by the proximity of the customer, the RC combination operates as a filter to increase the rectification efliciency in leg 108 and thereby increase the average value of the signal therein. It will be appreciated, therefore, that a positive DC signal now appears between terminal 104 and ground, such signal representing a logic 1 and causing AND gate 50 to deliver an output.

Referring to FIG. 4, the output of AND gate 50 is applied to SCR gate 114a to place SCR 114 in conduction. Except for the voltage drop through the cathode-anode circuit of SCR 114, lead 124 is now at ground potential rather than at the positive supply potential. This change of potential on lead 124 is utilized by circuitry (not shown) to cause the delivery of a logic 1 signal at output 74 (FIG. 2).

The commutating capacitors 122 prevent more than one SCR from conducting at a given time by transmitting a negative transient to the anodes of the other SCRs when one of the SCRs is gated. Therefore, if an unscrupulous customer, noting that two articles are available at a price of 20 each, should attempt to select both such articles simultaneously, AND gates 50 and 56 will both deliver an output but only one of the SCRs 114 and 120 will go into conduction.

When output 74 of the interlock and selection control circuitry 58 is placed at the 1 level, the output of NOR gate 98 assumes the 0 level to prevent deposit value information from totalizer 26 from reaching AND gates 50, 52, 54 and 56 until the vend cycle is completed; thus, in the instant example, the output of AND gate 38 returns to the 0 level. At the same time, circuitry 58 starts timer 60 which, as its first function, effects the acceptance of the coins in escrow. This is illustrated in the timing graph of FIG. 3 where it will be noted that shortly thereafter a vend pulse is produced. The vend pulse is produced by timer 60 and appears along line 62 to, in turn, operate AND gate 82 to effect energization of the dispensing structure 90. On the other hand, AND gates 84, 86 and 88, of course, do not respond since outputs 76, 78 and 80 are at the 0 level. The time lag between coin acceptance and initiation of the vend pulse allows the interlock circuitry to stabilize. As its final function, timer 60 produces a reset pulse as illustrated in FIG. 3 and delivers the same to totalizer 26 along line 64. Additionally, the reset command is delivered to control circuitry 58 as indicated in FIG. 2; the electrical interlock illustrated in FIG. 4 is reset by application of the reset command (a negative pulse) to the reset terminal, the negative pulse being conducted to the conducting SCR by the commutating capacitors 122 to return the conducting SCR to the nonconductive state.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In a multiple selection dispensing machine: a plurality of article dispensing structures; proximity sensing means having a sensing component corresponding to each of said structures respectively;

means mounting said components at locations where a consumer may place a portion of his body in relatively close proximity to a selected component; and

apparatus coupled with said structures and said sensing means and operable to initiate operation of the structure corresponding to the selected component in response to sensing of the consumer by the sensing means,

said sensing means exhibiting substantial electrical capacitance at the selected component When the consumer is proximal to the latter,

said apparatus including detector means having a sensing circuit coupled with each of said components respectively, each circuit having a first standby electrical state and a second electrical state assumed when the consumer is in sufiiciently close proximity to the component coupled therewith to cause the intro duction of said substantial capacitance into the circuit, whereby the selection of an article dispensed by a particular structure is indicated by a change-ofstate of the corresponding circuit from the first to the second state thereof.

2. The invention of claim 1;

said detector means including a signal source for providing an oscillatory electrical signal having components of opposite polarity,

each of said circuits having an output, and being pro vided with rectifier means coupled with said source and responsive to said signal for separating said opposite polarity components thereof, and summing means coupled with said rectifier means and responsive to the separate components of said signal for providing a summation of the average values of said separate components at said output, the sensing component coupled with the circuit being arranged in said summing means to cause a change in the average value of one of said separate components when the sensing component exhibits said substantial capacitance, whereby to alter the summation at said output to provide said change-of-state.

3. The invention of claim 1;

said sensing means including a conductive structural assembly of the machine,

each of said components comprising a conductive plate,

said mounting means positioning said plates in spaced relationship to one another and said assembly.

4. In a money-actuated, multiple selection vending machine:

means for registering the value of money deposited in the machine;

a plurality of dispensing structures, each operable to dispense an article of predetermined price;

proximity sensing means having a plurality of sensing components, each representing the articles dispensed by a corresponding structure;

means mounting said components at locations where a customer may place a portion of his body in relatively close proximity to a selected component; and

apparatus coupled with said structures, said registering means, and said sensing means and responsive to the registering and the sensing means for initiating operation of one of said structures to vend a selected article when a deposit is registered at least equal to the price of the selected article and the customer is sensed by the corresponding sensing component,

said sensing means exhibiting substantial electrical capacitance at the selected component when the customer is proximal to the latter,

said apparatus including detector means having a sensing circuit coupled with each of said components respectively, each circuit having a first standby electrical state and a second electrical state assumed when the customer is in sufiiciently close proximity to the component coupled therewith to cause the introduction of said substantial capacitance into the circuit, whereby the selection of an article represented by the corresponding component is indicated by a change-of-state of the respective circuit from the first to the second state thereof.

5. The invention of claim 4:

said apparatus further including an electrically responsive control device for actuating each of said structures respectively in response to registration of a deposit at least equal to the price of the corresponding article and sensing of the customer by the corresponding sensing component, and means intercoupling said devices and preventing operation of more than one of said devices at a time, whereby to provide an electrical interlock to preclude multiple vending on a single deposit.

6. The invention of claim 4:

said apparatus further including means for accepting said deposit in response to registration thereof and sensing of the customer, and means for thereafter effecting actuation of said one structure.

7. A proximity detector comprising:

a signal source for providing an oscillatory electrical signal having components of opposite polarity; and

a sensing circuit coupled with said source and having an output,

said circuit including rectifier means responsive to said signal for separating said components and summing means coupled with said rectifier means and responsive to the separate components for providing a summation of the average values thereof at said output,

said summing means being provided with sensing means for introducing capacitance into the Summing means in the presence of :a foreign body adjacent the sensing means, the latter being arranged in said summing means to cause a change in the average value of one of said separate components upon said introduction of capacitance into the summing means, whereby the presence of said body in sufficiently close proximity to the sensing means to add capacitance to the summing means is indicated by a change in the summation at said output.

8. The invention of claim 7:

said summing means having a pair of legs for receiving respective separate components from the rectifier means,

the leg receiving said one component being connected to said sensing means and cooperating with the latter, when said body is present, to filter said one component and thereby increase the average value thereof.

9. The invention of claim 8:

said summing means having a pair of inputs,

each of said legs being connected in series between a corresponding input and said output and having an impedance element therein,

said sensing means including a conductive plate coupled to the input of the leg receiving said one component;

and

a neutralizing capacitor coupled to the input of the leg receiving the other of said separate components for offsetting the stray capacity of said plate,

said summing means including a condenser coupled to said output having a substantially greater capacitance than said neutralizing capacitor.

10. In a money-actuated, multiple selection vending m achine means for registering the value of money deposited in the machine;

a plurality of dispensing structures, each operable to dispense an article of predetermined price;

proximity sensing means having a plurality of sensing components, each representing the articles dispensed by a corresponding structure;

means mounting said components at locations where a customer may place a portion of his body in relatively close proximity to a selected component;

apparatus coupled with said structures, said registering means, and said sensing means and responsive to the registering and the sensing means for initiating operation of one of said structures to vend a selected article when a deposit is registered at least equal to the price of the selected article and the customer is sensed by the corresponding sensing component,

said apparatus including a plurality of AND gates each having a pair of inputs and an output, means responsive to each of said outputs for actuating a corresponding structure, and circuitry coupled with each of said components respectively for delivering an electrical signal to one of the inputs of a corresponding AND gate when a customer is sensed by the component; and

circuit means coupling said registering means with the other of said inputs of each AND gate for delivering electrical signals thereto bearing deposit value information, and including means responsive to initiation of operation of any of said struct-ures for preventing delivery of said information signals to said other inputs during vending of the selected article.

References Cited UNITED STATES PATENTS 1,701,975 2/1929 Gunn 340-258 X 2,800,988 7/1957 Timms. 2,876,883 3/1959 Baker et a1. 3,002,602 10/ 1961 Giepen. 3,067,364 12/1962 Rosso. 3,254,313 5/1966 Atkins et al 340-258 X 3,278,079 10/1966 Guard 194-10 X 3,313,960 4/1967 Borys 340--258 X 3,333,160 7/1967 Gorski 340-258 X SAMUEL F. COLEMAN, Primary Examiner.

U.S. c1. X.R. 

